Water heater only luke warm from engine heat.

kloudie1 · Sep 24, 2016

Looks like it could be. I'd try opening it fully.. if already open, and not heating, there is probably an air lock in the coolant lines and the system needs to be bled to gat all the air out of the coolant hoses going to/from the water heater.

Gunni · Sep 24, 2016

Yes, that is an add-on valve that someone has put on your engine coolant feed line, not OEM.

Benny17441 · Sep 24, 2016

You do not indicate for how long you are running the engine. In colder climates it can take a few hours of straight motoring to heat the water.

Skipper · Sep 25, 2016

Benny17441 said:
You do not indicate for how long you are running the engine. In colder climates it can take a few hours of straight motoring to heat the water.

Second.
Even in warm waters it takes mine an hour + of running to get the water "hot". Even longer for it to reach engine temp.
It takes a lot of energy to heat 6 gallons of water to 165 degrees, especially with the coolant that provides the heat only allowed to get to 165, with the engine exchanger and thermostat preventing more heat from entering the water heater.

MitchM · Sep 25, 2016

i'm curious what the purpose is of that add on valve in the picture . on most HW heaters one of the engine hoses feeds into a sealed stainless tube in a loop inside the HW H. the outgoing hose takes the hot antifreeze out from the stainless tube loop.. having that valve which looks like it's between the intake hose and the outgo hose doesn't make sense. since the sealed stainless tube forms a sealed a loop inside the hw h, the heat transferred to the loop's stainless, from carrying the hot engine antifreeze through it , transfers its heat to the x gallons of h 2 0 in the tank. i'd find it unlikely that there's an air lock in the continuous loop from engine hose in, through the stainless loop, to engine hose out. that antifreeze, under pressure from the engine's 'fresh water ' aka antifreeze pump, is constantly circulating, under pump pressure , through the engine's counterflow heat exchanger, then goes back into the main antifreeze tank. Dx: can you measure the temp of the external surface of the engine to HW input heater hose, compare that to the operating temp of your engine, and then to the temp of the HW output engine hose?
.

RoyS · Sep 25, 2016

This year I modified my water system to by-pass the heat exchanger completely until the coolant reaches 160F. The water heater is always in the circuit. My two cylinder Yanmar 2qm15 will bring the 6 gallon hot water tank from 60F to 100F at idle in about 1 hour. It would probably bring 70F water to 100F in 45 minutes or so. Engine temperature is stable otherwise in all operating conditions.

Hello Below · Sep 25, 2016

MitchM said:
i'm curious what the purpose is of that add on valve in the picture .

Possibly in line with a hydronic (Espar or Webasto) heating system?

JamesG161 · Sep 25, 2016

MitchM said:
i'm curious what the purpose is of that add on valve in the picture

I am guessing....

Water temperature manual regulator.
___________
My 50 Hp engine't thermostat is set ≈185°F ( scalding temperature is 140°+ and ≈180°+ is dish sanitizing temps)

Jim...

Ralph Johnstone · Sep 25, 2016

JamesG161 said:
I am guessing....

Water temperature manual regulator.

Got to agree with you there. At first glance I thought the valve was something exotic and there was a sensing element going into "I don't know what ". But it would have to get into the potable hot water loop to be able to automatically control the temperature "but it just ain't so". It's simply a throttling valve hung from the side of the tank. Unfortunately it doesn't control anything.

During the start up from cold, you want the antifreeze flow at a max. to quickly heat the potable water. This doesn't help if it's throttled. Once you are up up temperature on the potable water, you'd have to shut this valve off to control anything. It just doesn't work automatically, no matter how you look at it.

However, that doesn't solve you problem. Try investing in an infrared temperature gun. I understand from others they're pretty cheap from Harbour Freight and are good enough as you're only after rough temperatures. This will tell you who's giving up heat to whom and where. As a shot in the dark, try removing the valve and re-connect the hoses to see if it has a restriction in it. Leave it out as it doesn't help you. Let us know what happens.

Allan12210 · Sep 25, 2016

Ralph has the best suggestion....remove that valve completely and re attach the hoses directly. If there is no restriction things shoul come up to temperature. Afterwards, consider adding a thermostatic mixing valve to protect yourself automatically from scalding. Here is the link for how I did mine.

http://forums.sailboatowners.com/index.php?threads/thermal-mixing-valve.173481/

Its really nice to have a passive controller and not have to try and throttle the engine loop to control temperature.

RoyS · Sep 26, 2016

By all means add a mixing valve to the hot water outlet. Also I added a temperature gauge there as well. I purchased a stainless dial temperature gauge with a long probe from a brewers supply that always displays the internal water heater temperature. Simply install it in a T fitting at the outlet with the mixing valve on the other leg. I can tell at a glance if the water is hot enough to shower with.

DougM · Sep 26, 2016

That pipe fitting on the front of the water heater simply looks like "T" that was put into the line for either bleeding air out of it or adding antifreeze. Its in the same line and doesn't actually attach to the insides of the water heater. It appears to be held in a high position in the line with zip ties.

sailrj · Sep 26, 2016

Had the same problem on our Oceanis 351 with the 18 year old Atwood water heater only getting luke warm . Took the hoses off the heat exchanger and discovered that the "double walled" heat exchanger consisted of the aluminum coil and connectors lined with a polymer tube. The polymer tube separated from the aluminum coil and collapsed, restricting flow. Managed to fish the lining out and the the exchanger worked better than ever. Used it for 5 months to get us home and have since replaced the water heater. Just my experience.

pateco · Sep 28, 2016

Is this a raw water cooled engine? On my Hunter 31 with a 2gm no matter how long you ran the motor the hot water would not get hot.

Gunni · Sep 28, 2016

The place to bleed air in that H/W heater loop is up high near the engine. I have a schrader valve to do that.

onlinelee · Oct 6, 2016

This post is not totally unrelated, more a issue I had with the european version of this heater " Quick " and its installation on my B361. Earlier this year on a day sail I let a crew member drain a water tank, by doing this the install then pumps water from the only other place there is water, the hot water tank, this was then fully drained too.
A few days later and ignorant to what my crew had done I took the boat out again for a day sail.

A few days later I returned to the boat to do some jobs, I pressurised the water system and to my surprise coolant started to poor out of the engine coolant overflow. What had happened was the coil inside the heater had been fried on that last day sail and ruptured as a result of having no fresh water in the tank.

Im about to install another boiler, any ideas on what could be installed to avoid this happening again would be appreciated.

Benny17441 · Oct 6, 2016

I don't see how the heating coil may have "fried" when you are away from shorepower so it likely happened at the dock. The water heater or "boila" should have a breaker switch in the main electrical panel to shut Off the power when not in use and especially after draining. I don't think you need to look for a fail safe gizmo but just a sound protocol or procedure regarding what to do when working on the heater or water tank.

onlinelee · Oct 6, 2016

Benny, in this instance Im afraid you are wrong, well, at least in part. Im sure you are aware the boiler has a coolant filled coil and an electric element. Clearly the element only works when connected to shore power, this side is protected as you say. Im afraid the coil is not protected, its a design flaw, in my humble opinion.

My boat was not and had not been connected to shore power. Maybe I used the wrong word ( Fried ) I should have said ruptured caused by engine coolant overheating a coil that was 13 years old and clearly coming to the end of its life. Donvanv, Im really sorry to have partly hi-jacked your thread.